MSTest Parser failed

I am trying to use VSTest instead of MSTest because of VS2012.
In VS2012 .vsmdi is not anymore editable and Microsoft encourages to use VSTest.
So I create a command task "VSTest" which generates a result file as MSTest and I created a "MSTest Parser" task.
But it doesn't work, I have always the same failure reason in my logs:
"Failing task since test cases were expected but none were found."
n.b: The result file is generated